An underwater imaging device based on hollow square ring laser illumination

Abstract

The application discloses an underwater imaging device based on hollow square ring laser illumination, comprising a transmitting optical system, a receiving optical system, a system controller and an image display, the transmitting optical system comprises a laser group, a ring light modulation module and a ring lens modulation module, and is used for realizing underwater laser illumination; the receiving optical system is composed of a low-illumination imaging detector and a zoom imaging lens, and is used for collecting target information light under different imaging fields of view and realizing underwater imaging; the system controller is connected with the transmitting optical system and the receiving optical system in communication, and is used for coordinating and controlling each module in the device; and the image display is used for image display under the control of the system controller. The device has the advantages of low cost, small volume, low energy consumption, high portability and clear imaging, can be flexibly used for underwater security monitoring, handheld camera equipment, underwater robot imaging load and multiple purposes, and has a wide market space.

Description

Technical Field

[0001] This invention relates to the field of underwater lighting and imaging equipment technology, and in particular to an underwater imaging device based on hollow square ring laser illumination. Background Technology

[0002] Underwater optical imaging has wide applications in underwater topographic mapping, aquaculture, environmental monitoring, and underwater operations. Compared to acoustic and microwave methods, it offers advantages such as high imaging resolution, good color reproduction, and rich information acquisition for short-range underwater detection tasks. However, due to the strong absorption of natural light by water, underwater environments are mostly dark, necessitating active illumination to enhance the imaging of reflected light from the environment and the target.

[0003] Common active illumination methods, such as broadband LEDs and halogen lamps, suffer from high overall power consumption, limited illumination modes, low conversion efficiency, and poor transmission directionality. Their wide-angle divergent illumination method leads to significant intersections between the illumination and imaging optical paths, introducing substantial backscattered light into the imaging field of view, causing image blurring. This is particularly problematic for active illumination requirements in turbid water. Furthermore, the broadband nature of the light source and the selective absorption by the water cause severe energy attenuation, limiting the illumination distance. While increasing the illumination power can extend the distance, it also results in significant energy waste. Lasers, with their narrow spectrum, good directionality, and concentrated energy, are excellent underwater illumination sources. Although distance gating and synchronous scanning techniques can reduce backscattered light interference to some extent, such imaging systems typically require light sources with narrow spectral width, high energy, good coherence, and high stability, such as frequency-doubled Nd:YAG lasers or argon-ion lasers. Therefore, they generally suffer from drawbacks such as high cost, large size, and system complexity, failing to meet the needs of practical applications. Therefore, the illumination method, power consumption, cost, size, weight, and complexity of the light source are important factors affecting the performance of existing underwater imaging devices. Summary of the Invention

[0004] The purpose of this invention is to provide an underwater imaging device based on hollow square ring laser illumination. This device has the advantages of low cost, small size, low energy consumption, high portability, and clear imaging. It can be flexibly used for multiple purposes such as underwater security monitoring, handheld camera equipment, and underwater robot imaging payloads, and has a broad market potential.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] An underwater imaging device based on hollow square ring laser illumination, the device comprising a transmitting optical system, a receiving optical system, a system controller, and an image display, wherein:

[0007] The transmitting optical system includes a laser array, a ring light modulation module, and a ring lens modulation module, used to achieve underwater laser illumination. The ring light modulation module modulates the beam diameter, spot shape, and divergence angle of the laser beam emitted by the laser array to form a hollow ring laser with adjustable edge thickness. The ring lens modulation module adjusts the elevation angle of the illumination laser beam without affecting the imaging and light collection.

[0008] The receiving optical system consists of a low-light imaging detector and a zoom imaging lens, used to collect target information light under different imaging fields of view to achieve underwater imaging.

[0009] The system controller is connected and communicates with the transmitting optical system and the receiving optical system respectively. It includes an embedded microcontroller, a clock module, an operational amplifier module and a communication module. It is used to coordinate and control the various modules in the device, including laser beam output switch, optical power adjustment, laser beam expansion diameter adjustment, laser divergence adjustment, laser pitch adjustment and lens zoom, so as to realize automatic control of the imaging process.

[0010] An image display is used to display images under the control of a system controller.

[0011] A hollow square ring laser illumination device, the device comprising a ring light modulation module and a ring lens modulation module, wherein:

[0012] The ring light modulation module consists of a collimating and beam-expanding lens group, a line beam lens, and a convex lens. It is used to modulate the high-energy beam emitted from each semiconductor laser tube at a fixed divergence angle. The specific modulation process is as follows: First, collimation and beam expansion are performed to convert the beam into a collimated parallel beam with an adjustable spot diameter. Then, the line beam lens is used to modulate the circular spot into a diverging "I"-shaped linear spot. By moving the convex lens coaxial with the line beam lens at the rear end, the divergence angle of the "I"-shaped linear spot is adjusted to obtain a parallel linear laser beam. Each light source and the ring light modulation module can obtain a parallel "I"-shaped linear beam with an adjustable divergence angle. Then, through the effective combination of the four laser beams (upper, lower, left, and right), a hollow square ring laser with adjustable edge width and divergence angle is formed.

[0013] The ring lens modulation module consists of a set of coaxial hollow ring lenses. By adjusting the distance between the two lenses, the pitch angle of the hollow square ring laser generated by the laser group and the ring light modulation module can be adjusted, thereby achieving a high degree of matching between the illumination divergence angle and the imaging field of view, and improving the illumination and imaging effects.

[0014] As can be seen from the technical solution provided by the present invention, the above-mentioned device has the advantages of low cost, small size, low energy consumption, high portability, and clear imaging. It can be flexibly used for multiple purposes such as underwater security monitoring, handheld camera equipment, and underwater robot imaging payload, and has a broad market space. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the underwater imaging device based on hollow square ring laser illumination provided in an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the horizontal illumination and imaging optical path principle of the device described in the embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of beam modulation using a linear lens according to an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, and do not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0020] like Figure 1 The diagram shown is a schematic representation of an underwater imaging device based on hollow square ring laser illumination provided in an embodiment of the present invention. The device includes a transmitting optical system, a receiving optical system, a system controller, and an image display, wherein:

[0021] The transmitting optical system includes a laser array, a ring light modulation module, and a ring lens modulation module, used to achieve underwater laser illumination. The ring light modulation module modulates the beam diameter, spot shape, and divergence angle of the laser beam emitted by the laser array to form a hollow ring laser with adjustable edge thickness. The ring lens modulation module adjusts the elevation angle of the illumination laser beam without affecting the imaging and light collection.

[0022] The receiving optical system consists of a low-light imaging detector and a zoom imaging lens, used to collect target information light under different imaging fields of view to achieve underwater imaging.

[0023] The system controller is connected and communicates with the transmitting optical system and the receiving optical system respectively. It includes an embedded microcontroller, a clock module, an operational amplifier module and a communication module. It is used to coordinate and control the various modules in the device, including laser beam output switch, optical power adjustment, laser beam expansion diameter adjustment, laser divergence adjustment, laser pitch adjustment and lens zoom, so as to realize automatic control of the imaging process.

[0024] An image display is used to display images under the control of a system controller.

[0025] In a specific implementation, the device also includes a housing for sealing, connecting, protecting, and fixing other modules, and providing necessary counterweight for the overall device.

[0026] In the transmitting optical system, the laser array uses semiconductor laser tubes, which are distributed at the top, bottom, left, and right positions of the receiving optical system. This embodiment uses semiconductor green laser tubes, which have advantages such as low cost, small size, light weight, low power consumption, and easy integration. The output power of a single tube can reach 500mW, and the overall power consumption is less than 10W. Compared with broadband illumination sources such as high-power LEDs, it not only significantly reduces illumination power consumption, but also has higher transmission efficiency and anti-attenuation capability underwater due to the better directionality and narrower spectral width of the laser beam, thus enabling a longer illumination distance. Compared with all-solid-state lasers and argon-ion lasers, semiconductor green laser tubes not only have advantages in size and cost, but also have less coherence and diffraction effects caused by underwater imaging.

[0027] The ring light modulation module consists of a collimating and beam-expanding lens group, a line beam lens, and a convex lens. It is used to modulate the high-energy beam emitted from each semiconductor laser tube at a fixed divergence angle. The specific modulation process is as follows: First, collimation and beam expansion are performed to convert the beam into a collimated parallel beam with an adjustable spot diameter. Then, the line beam lens is used to modulate the circular spot into a diverging "I"-shaped linear spot. By moving the convex lens coaxial with the line beam lens at the rear end, the divergence angle of the "I"-shaped linear spot is adjusted to obtain a parallel linear laser beam. Each light source and the ring light modulation module can obtain a parallel "I"-shaped linear beam with an adjustable divergence angle. Then, through the effective combination of the four laser beams (upper, lower, left, and right), a hollow square ring laser with adjustable edge width and divergence angle is formed.

[0028] like Figure 2The diagram shows the horizontal illumination and imaging optical path principle of the device according to an embodiment of the present invention. The diagram includes: 1-Device housing; 2-Left-side semiconductor laser tube; 3-Left-side collimating beam expander group; 4-Left-side linear lens; 5-Left-side convex lens; 6-Hollow ring lens group; 7, 8-Hollow ring lenses; 9-Right-side semiconductor laser tube; 10-Right-side collimating beam expander group; 11-Camera; 12-Right-side linear lens; 13-Zoom lens; 14-Right-side convex lens. (Reference) Figure 2 This technique modulates the divergent illumination laser into a linear laser beam and forms a square-ring illumination laser beam that matches the imaging field of view. During illumination, this effectively reduces the influence of backscattering from the illumination path and water within the imaging field of view, thus enhancing image quality. Linear lens ( Figure 2 (4 and 12) use Powell lenses, which produce linear beams with more concentrated energy compared to conventional divergent illumination light, while ordinary cylindrical lenses are limited in their linear effect by non-uniform Gaussian laser beams due to structural defects.

[0029] like Figure 3 The diagram illustrates the beam modulation of the linear laser beam by the linear lens according to an embodiment of the present invention. 15 represents the laser beam incident on the linear lens; 16 represents the linear laser beam modulated by the linear lens; 17 represents the incident laser cross-section of the linear lens; and 18 represents the emitted laser cross-section of the linear lens. The linear lens is designed with a complex two-dimensional aspherical curve and curved apex. By generating a large amount of spherical aberration, the light is redistributed along a straight line, reducing the light intensity in the central region while increasing the light intensity at the ends of the line. Therefore, the energy distribution of the modulated linear laser is more uniform.

[0030] The ring lens modulation module consists of a set of coaxial hollow ring lenses, such as... Figure 2 As shown in Figures 7 and 8, by adjusting the distance between the two lenses, the elevation angle of the hollow square ring laser generated by the laser array and the ring light modulation module can be adjusted, thereby achieving a high degree of matching between the illumination divergence angle and the imaging field of view, improving the illumination and imaging effects. Since the center of the ring lens is a hollow structure, the target reflected light can directly enter the imaging module without refraction, effectively realizing the multiplexing of the illumination and imaging optical paths, avoiding redundant reflective devices, making the entire optical path structure more compact, and effectively compressing the internal space of the device.

[0031] In specific implementation, the imaging detector of the receiving optical system has low illumination and wide dynamic range, and the minimum sensitivity in color mode is 0.001 Lux, so as to better adapt to the underwater low light environment; the zoom imaging lens has an electric controllable function and ensures that the imaging field of view is ≤ the ring laser divergence angle.

[0032] In addition, the ring light modulation module can modulate and generate square ring, circular ring or polygonal ring illumination laser, and the corresponding light source for generating the ring laser beam is a single laser or a combination of multiple lasers with a beam splitting structure.

[0033] The linear lens in the ring light modulation module can be a Powell lens, cylindrical lens, wave mirror, or DOE diffraction element; the semiconductor laser source can be replaced by a narrow-spectrum monochromatic light source with a small divergence angle.

[0034] The collimating and beam-expanding lens group in the ring light modulation module can be replaced by a combination of concave and convex lens groups;

[0035] The embedded microcontroller in the system controller can be replaced by a DSP processor or a system-on-a-chip.

[0036] This invention also provides a hollow square ring laser illumination device, the device comprising a ring light modulation module and a ring lens modulation module, wherein:

[0037] The ring light modulation module consists of a collimating and beam-expanding lens group, a line beam lens, and a convex lens. It is used to modulate the high-energy beam emitted from each semiconductor laser tube at a fixed divergence angle. The specific modulation process is as follows: First, collimation and beam expansion are performed to convert the beam into a collimated parallel beam with an adjustable spot diameter. Then, the line beam lens is used to modulate the circular spot into a diverging "I"-shaped linear spot. By moving the convex lens coaxial with the line beam lens at the rear end, the divergence angle of the "I"-shaped linear spot is adjusted to obtain a parallel linear laser beam. Each light source and the ring light modulation module can obtain a parallel "I"-shaped linear beam with an adjustable divergence angle. Then, through the effective combination of the four laser beams (upper, lower, left, and right), a hollow square ring laser with adjustable edge width and divergence angle is formed.

[0038] The ring lens modulation module consists of a set of coaxial hollow ring lenses. By adjusting the distance between the two lenses, the pitch angle of the hollow square ring laser generated by the laser group and the ring light modulation module can be adjusted, thereby achieving a high degree of matching between the illumination divergence angle and the imaging field of view, and improving the illumination and imaging effects.

[0039] In a specific implementation, the ring light modulation module modulates and generates square ring, circular ring, or polygonal ring illumination lasers. The corresponding light source for generating the ring laser beam is a single laser or a combination of multiple lasers with a beam splitting structure.

[0040] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0041] In summary, the device described in the embodiments of the present invention has the following advantages:

[0042] 1. A hollow ring illumination laser that matches the rectangular imaging field of view is generated by a ring light modulation module. During the illumination process, the overlap between the illumination light path and the imaging field of view can be effectively reduced. The forward scattered light of the hollow ring illumination laser is used for field illumination, avoiding the interference of backscattered interference light on the target reflected light. This significantly improves the imaging quality and imaging distance of the image sensor, especially enhancing its adaptability to turbid water bodies.

[0043] 2. The light source in the device uses a low-cost, lightweight semiconductor laser as the illumination source. It is small in size and has low power consumption. Compared with broadband illumination sources such as high-power LEDs, the light source has a narrower spectrum, stronger transmission directionality, and more concentrated energy, which can more effectively reduce water absorption attenuation, improve energy utilization, and reduce lighting power consumption.

[0044] 3. This invention generates a linear laser beam by modulating it with a linear lens. Compared with traditional divergent illumination light, the energy is more concentrated, and the divergence angle and width of the laser beam are adjustable. It can better adapt to the ring light modulation module in different underwater environments. The linear lens is preferably a Powell linear lens, which modulates the divergent illumination laser into a linear laser beam. Compared with ordinary cylindrical lenses, it reduces the limitation of the linear effect by the non-uniform Gaussian laser beam.

[0045] 4. The hollow ring lens module of the present invention has a hollow structure, so the target reflected light can directly enter the imaging module without refraction, effectively realizing the reuse of the illumination and imaging optical paths, avoiding unnecessary reflective devices, and making the optical path structure of the device more compact.

[0046] 5. The device of the present invention has the advantages of low cost, small size, low energy consumption, high portability and clear imaging. It can be flexibly used for multiple purposes such as underwater security monitoring, handheld camera equipment, and underwater robot imaging payload, and has a broad market space.

[0047] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. An underwater imaging device based on hollow square ring laser illumination, characterized in that, The device includes a transmitting optical system, a receiving optical system, a system controller, and an image display, wherein: The transmitting optical system includes a laser array, a ring light modulation module, and a ring lens modulation module, used to achieve underwater laser illumination. The ring light modulation module modulates the beam diameter, spot shape, and divergence angle of the laser beam emitted by the laser array to form a hollow ring laser with adjustable edge thickness. The ring lens modulation module adjusts the elevation angle of the illumination laser beam without affecting the imaging and light collection. In the transmitting optical system, the laser array uses semiconductor laser tubes, which are respectively distributed at the top, bottom, left, and right positions of the receiving optical system; The ring light modulation module consists of a collimating and beam-expanding lens group, a line beam lens, and a convex lens. It is used to modulate the high-energy beam emitted from each semiconductor laser tube at a fixed divergence angle. The specific modulation process is as follows: First, collimation and beam expansion are performed to convert the beam into a collimated parallel beam with an adjustable spot diameter. Then, the line beam lens is used to modulate the circular spot into a diverging "I"-shaped linear spot. By moving the convex lens coaxial with the line beam lens at the rear end, the divergence angle of the "I"-shaped linear spot is adjusted to obtain a parallel linear laser beam. Each light source and the ring light modulation module can obtain a parallel "I"-shaped linear beam with an adjustable divergence angle. Then, through the effective combination of the four laser beams (upper, lower, left, and right), a hollow square ring laser with adjustable edge width and divergence angle is formed. The ring lens modulation module consists of a set of coaxial hollow ring lenses. By adjusting the distance between the two lenses, the pitch angle of the hollow square ring laser generated by the laser group and the ring light modulation module can be adjusted, thereby achieving a high degree of matching between the illumination divergence angle and the imaging field of view, and improving the illumination and imaging effects. The receiving optical system consists of a low-light imaging detector and a zoom imaging lens, used to collect target information light under different imaging fields of view to achieve underwater imaging. The system controller is connected and communicates with the transmitting optical system and the receiving optical system respectively. It includes an embedded microcontroller, a clock module, an operational amplifier module and a communication module. It is used to coordinate and control the various modules in the device, including laser beam output switch, optical power adjustment, laser beam expansion diameter adjustment, laser divergence adjustment, laser pitch adjustment and lens zoom, so as to realize automatic control of the imaging process. An image display is used to display images under the control of a system controller.

2. The underwater imaging device based on hollow square ring laser illumination according to claim 1, characterized in that, The imaging detector of the receiving optical system has low illumination and wide dynamic range, and the lowest sensitivity in color mode is 0.001 Lux, so as to better adapt to the low light environment underwater. The zoom imaging lens has an electrically controllable function and ensures that the imaging field of view is ≤ the ring laser divergence angle.

3. The underwater imaging device based on hollow square ring laser illumination according to claim 1, characterized in that, The ring light modulation module modulates and generates square ring, circular ring, or polygonal ring illumination lasers. The corresponding light source for generating the ring laser beam is a single laser or a combination of multiple lasers with a beam splitting structure.

4. The underwater imaging device based on hollow square ring laser illumination according to claim 1, characterized in that, The linear lens in the ring light modulation module is a Powell lens, cylindrical lens, wave mirror or DOE diffraction element. The semiconductor laser tube is replaced by a narrow-spectrum monochromatic light source with a small divergence angle.

5. The underwater imaging device based on hollow square ring laser illumination according to claim 1, characterized in that, The collimating and beam-expanding lens group in the ring light modulation module can be replaced by a combination of concave and convex lens groups; The embedded microcontroller in the system controller can be replaced by a DSP processor or a system-on-a-chip.

6. A hollow square ring laser illumination device, characterized in that, The device includes a ring light modulation module and a ring lens modulation module, wherein: The ring light modulation module consists of a collimating and beam-expanding lens group, a line beam lens, and a convex lens. It is used to modulate the high-energy beam emitted from each semiconductor laser tube at a fixed divergence angle. The specific modulation process is as follows: First, collimation and beam expansion are performed to convert the beam into a collimated parallel beam with an adjustable spot diameter. Then, the line beam lens is used to modulate the circular spot into a diverging "I"-shaped linear spot. By moving the convex lens coaxial with the line beam lens at the rear end, the divergence angle of the "I"-shaped linear spot is adjusted to obtain a parallel linear laser beam. Each light source and the ring light modulation module can obtain a parallel "I"-shaped linear beam with an adjustable divergence angle. Then, through the effective combination of the four laser beams (upper, lower, left, and right), a hollow square ring laser with adjustable edge width and divergence angle is formed. The ring lens modulation module consists of a set of coaxial hollow ring lenses. By adjusting the distance between the two lenses, the pitch angle of the hollow square ring laser generated by the laser group and the ring light modulation module can be adjusted, thereby achieving a high degree of matching between the illumination divergence angle and the imaging field of view, and improving the illumination and imaging effects.

7. The hollow square ring laser illumination device according to claim 6, characterized in that, The ring light modulation module modulates and generates square ring, circular ring, or polygonal ring illumination lasers. The corresponding light source for generating the ring laser beam is a single laser or a combination of multiple lasers with a beam splitting structure.

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